1. Field of the Invention
The present invention relates to a semiconductor carrier suitable for mounting a semiconductor device with a high density and method for manufacturing the same.
2. Description of the Related Art
The semiconductor carrier for mounting the semiconductor device is known in the art, for example, as disclosed in the "Electric Component & Technology Conference", No. 46, pp. 727-732. FIG. 4 depicts a cross section of the carrier, in which a copper interconnection pattern 41, a base layer 42 consisting of a polyimide film, and an adhesive layer 43 consisting of a thermoplastic polyimide construct a tape substrate 44. A through hole bump 45 to be connected electrically with a chip is formed in the tape substrate 44. A cover resist layer 48, which includes an aperture 46 for connecting the semiconductor carrier with a mount board electrically and a slit 47 for bonding, is formed on the copper interconnection pattern 41.
In the above-mentioned conventional semiconductor carrier, a substance of the adhesive layer 43 and a technology for forming a through hole in the base layer 42 and adhesive layer 43 to form the through hole bump 45 greatly affect the performance and reliability of the semiconductor carrier. Essential properties required for the adhesive layer 43 are an advantageous heat resistance, moisture resistance, adhesion and low stress which enable to endure various treatments suffered from post-processes such as a process for mounting the semiconductor carrier on the mount board as well as a drug resistance without degrading its characteristics through plating and cleaning processes.
On the other hand, the through hole forming method for forming the through hole bump 45 also greatly affects the performance and reliability of the semiconductor carrier. A method using a laser such as an excimer, carbonic acid gas or YAG laser is generally well known as the through hole forming method. In the method, however, process conditions are unstable so that an etching remainder or sludge may be left on the via bottom. The method further includes a disadvantage that a reliable bump can not be formed because a thermal damage is given to a surface of the copper interconnection pattern 41 according to a type of the laser, resulting in an unstable adhesion of the interface between the copper interconnection pattern 41 and the through hole bump 45.
The formation of the through hole by the laser reduces the throughput and makes a limitation for the yield. In addition, it is not suitable for the mass production and is disadvantageous with respect to the cost. Further, the carbonic acid gas laser and YAG laser are difficult to form a fine through hole because of their long wavelengths. It is desirable for the method as the means to solve such the disadvantages that the adhesive layer 43 has a photosensitivity and that the through hole is formed by the conventional photolithography process.
There is a subject under consideration to construct the semiconductor carrier with an adhesive that has the advantageous heat resistance, moisture resistance, adhesion, low stress and drug resistance as described above. The adhesive should also have the photosensitivity and advantageous resolution, and enable to form a fine through hole by the conventional photolithography process.
The known adhesives with photosensitivity include those of polyimide series as disclosed in JPA 4-337380 and those of epoxy series as disclosed in JPA 6-19134 and JPA 6-27660.
The photosensitive adhesive of polyimide series, however, has a particularly large contraction stress caused during setting. The stress affects to bend the semiconductor carrier unfavorably, and prevents a practical semiconductor carrier to be formed. On the other hand, the photosensitive adhesive of epoxy series is difficult to form a reliable semiconductor carrier because of its essential disadvantage in the heat resistance and moisture resistance. In addition, it has a low resolution and is not suitable for forming the fine through hole.